This invention relates to tube bags which do not have gussets in their lateral edges.
Specifically the invention relates to an improvement in producing flat continuous tube style, bottom sealed, plastic bags which have flush cut top openings. Presently, flush cut top opening bags manufactured from a homogeneous plastic resin are well known. The problem encountered with these types of bags is that the inner surface of the bag tends to have a cohesive effect which makes the opening at the upper end of the bag very difficult. Consequently, the bag filling operation is slow and cumbersome due to the difficulty which the operator has in opening the upper end of the bag.
Various efforts have been made to ease the manner in which the upper end of the bag may be opened. One presently known method comprises the use of a chilled mandrel on the interior surface of the bag which causes stresses in the plastic film to produce a flaring of the top of the bag. However, such flaring is sometimes undesirable inasmuch as it makes the bag have an irregular shape.
Another method presently used in the manufacture of what is called a "tube turned" bag. The plastic film is extruded into a flat tube construction and then is printed. After printing, the tube is partially opened up and rotated three to five inches. The tube is then collapsed leaving the original creases spaced inwardly from the lateral margins of the bag. Such a process is cumbersome inasmuch as it requires rotation of the tube during the high speed manufacturing process.